High energy density galvanic cells can be prepared in a variety of forms including so-called button cells, cylindrical cells and flat ribbon cells. A great variety of organic solvents, electrolyte salts and anodically and cathodically active materials are known to be useful in such cells. Basically, such cells comprise a container, an anode containing anodic material, a cathode containing cathodic material reducible by the anodic material, a conductive electrolyte in contact with both anode and cathode, a non-conductive separator to prevent physical contact between anode and cathode and yet allow passage of electrolyte, and anode and cathode contacts to make an electrical circuit.
To be effective, the material employed as a cathode must either be conductive itself or must incorporate a conductivity aid such as carbon. The art generally employs the cathodically active material in coherent form made, usually, by tightly pressing, sintering or otherwise compacting the material. Very often a binder such as polytetrafluoroethylene is used. Metal screens are sometimes used to hold the active material together and to increase the physical strength of the formed cathode.
Iron sulfide, which is itself conductive, is known as a useful cathodic agent in galvanic cells. For instance, a cell utilizing an iron sulfide cathode is disclosed in U.S. Pat. No. 3,796,604. The cathodes of said patent employ both polytetrafluoroethylene and carbon in addition to the active iron sulfide. It will be appreciated, however, that where diluents such as carbon or binders are used, the resultant cells will suffer a decrease in their maximum energy/unit weight ratio since the amount of active material per unit of cell weight is necessarily lowered by the presence of such diluents.
U.S. Pat. No. 3,639,174 also describes a coherent iron sulfide-containing cathode. U.S. Pat. No. 3,796,606 describes compressed powders (not iron sulfide) as cathodic materials. Highly compressed powders are taught in "High Energy Batteries", Jasinski, Plenum Press, NY 1967, pp. 191 to 197. For low-drain situations, granular copper oxide is known to be useful as a cathodically active material; see "The Primary Battery", Heise et al., John Wiley and Sons, 1971, p. 195.